Method of mining coal



Feb, l0, 1925.-

- J. P. DAWSON METHOD oF MINING COAL Filed March 2G, 1924 H1 f Pavemen v g; 3) M rame/1FL '7. 5.

gwunoz Lf lP D a w s 0 I1 Snom@ I Patented Feb. 10, 1925.

UNITED STAT JOSEPH POWER DAWSON, OF CHARLESTON, WEST VIRGINIA.

METHOD OF MINING COAL.

Application filed March 26, 1924. Serial No. 702,106.

To all whom t may concern:

Be it known that I, JOSEPH POWER DAW- soN, residing at Charleston, in the county of Kanawha and State of West Virginia, and a citizen of the United States, have invented certain new and useful Improvements in Methods of Mining Goal, of which the following is a specification, reference being had to the accompanying drawing', forming a part thereof.

This invention relates to a method of mining coal, particularly bituminous coal, and has for its object to provide a method by which a body of coal lying in approximately horizontal position between a lower stratum, sometimes termed the pavement, of slate or other rock formation, and an overhanging or roof stratum of slate or the like, may be rapidly and safely mined'with safety to the miners and at the least possible expense.

In the mining of such bodies of coal, which are often many feet in width and length, it is usual to first cut parallel entries or passageways at suitable distances apart, thus dividing the body of coal into masses or blocks with two parallel sides. In the long wall system of mining, the block of coal between the two parallel entries is mined in slabs which are the masses of coal removed b-y a continuous cut of the cutting machine and the subsequent knocking or shooting down. The mining operation is usually conducted along only one side vof the block of coal at one time. Where successive slabs of coal of equal length are mined, difficulty is found in avoiding the of the roof or voverhanging wall without leaving at intervals pillars of coal or introducing other supports, usually timbers, which interfere with the regular operation of the mining machines. Extensive timbering of the mine is expensive and the leaving of large and numerous pillars is uneconomical, and both add to the difficulty of getting the coal out of the mine.

falling It is the purpose of my invention to provide a method by which the coal may be broken down in slabs in such manner that the operation may be conducted without risk of premature fa ling of the roof and with little need for timbering or leaving supporting pillars.

With the objects above indicated and other objects hereinafter explained in view,

my invention consists in the method hereinafter described and claimed. V

Referring to the drawing: Figure l is a-plan view of a body of coal blocked off by parallel entries;

Figure 2 is an elevation view of the body of coal from the entry 2 showing the area B of Figure l removed;

Figure 3 is an elevation view of the body of coal from the entry l showing the area C of Figure l removed;l

Figure 4 is a cross sectional view on line 4 4 of Figure l; and

Figure 5 is a cross sectional view on line 5-5 of Figure l.

In the drawings, l and 2 indicate parallel entries driven into the body of coal at such distance apart as to leave between them a mass or block of coal having parallel side walls. 3 indicates a relatively long slab mined by a mining machine, or otherwise, along and parallel with entry l and of such width as may be readily under-cut or otherwise cut by a mining machine so as to be subsequently knocked down, loaded on cars and removed. 4 indicates a second slab parallel with the slab 3 but of less length and 5 indicates a third slab? also parallel with slabs 3 and 4 but of less length than slab 4. 6, 7, 8 indicate successive slabs each parallel with the entry l and each of less length than the preceding slab. As this slabbing process goes forward, vtimbers are usually used for holding the roof up.` This slabbing is continued until the entry 2 is reached, unless, before it is reached, it is found that the area of roof from beneath which lthe coal has been removed becomes too'great to be supported without excessive timbering. The extent to which the slabbing operation begun from entry 1 can be carried will depend upon the character of roof, the tendency to fall, and the consequent need of timbering varying greatly in different mines and in different parts of the same mine. In the construction shown in the drawing, it is assumed that the slabbing operation begun from entry l is continuous until entry 2 is reached and the space indicated by A is cleared of coal. The face l2 left by the operation described is at an oblique angle to the line of the entries l and 2. The portion A of the block of coal which has been mined by the operation described is triangular and the roof llO over the portion of the block removed needs little orne-support near entry 2 but may needftimber support near entryfl. When the slabbing operations described have reached entry 2, the mining is continued by under-cutting and breaking down a relatively long slab 13 parallel vvitli ent-ry 2. A second slab 14 is then cut parallel with slab 13 but or' less length, and successivel slabs each of less length than the preced- 'ing slab are cut until entry 1 is reached, or until it is found necessary on account of risk et' premature falling of the root Witlinut encessive timbering tostop slabbing from that side. lllhenthe slabbino' operation begunirem.entry 2 is stoppen,

a space indicated by. B will be clearedy ofrlhe face 16 of the block ot coal will coal. be oblique to the entries but its Obliquity will. be oppesiteto that ci. the tace 12 lett by the slabbing. operation begun from entry 1.-

ln resuming` the mining7 slabbing is begun from entry 1, a relatively. long slab 17 being cut away along this entry. AA

second;slab 18k parallel with 17 but of less lengthis then cut away and so on untilv the entry 2 is reached or the slabbing is,l stepped.becausectl weaknessyoi the root, the liace19 leftfbeing oblique. to theentries and its Obliquity being opposite to that of face 16 andin thel same generaldirection with ace12. By this operation, a triangulaiu space C is cleared of coal.

The operation of slabbing Alirst Vtrom oneV spaces A, B, C, D, and E cleared of coal by` each operation.v being `substantially triangularivith the base of the triangle; alongv the entry at which the slabbing operation was begurn lneach of the slabbing operations, the longest slab is cut parallel with the next to the entry and the roof above this slab is so near the .support `afforded by the coal, or other roof suiport,v on the opposite side of the entry thatthere is little danger of its falling, and7 while the successive slabs are at increasing distances from theentry, they are successively shorter and the length of roof lettivithout sup-port successively de creased.

The method ci mining as thus far described shoivs the invention in its simplest form in order to bring out the idea of they mining of the coal by the progressive removal ot the roughly triangularrareas A5 B, C, D, and E. But in almost all mines, itLivill be necessary to vary the method of mining to suit the particular conditions in each mine depending` on the hardness oit' the coal, the Weight of the roof, and the like. 1n a mine withv average.. roof conditions, it will be `necessary to; timber along the irregular oblique faces, particularly in the middle portion as at 12, inorder to hold the roof up.

lt should be particularly noted that timbers may be used for either of tivo purposesMeither for holding` the roof up or forcing it to break at a desired point rather than Hush against. thev coal. As the space between two -obl-ique faces becomesv smaller as the slabbingi proceeds, the ease and practicabilityoffhclding the root'l up increases.

Very* important features o-i",this method ot coal mining are shown-at` 20 and 22. The cross sectioned space 20 indicates a pillaroftany desired size or shape left in the coal body asav support; for the roof. lt

should be noted that supporting pillars as at 2O can be lett Wherever.necessary Without seriously interfering withy the slabbingrand removing ot the coal. The crossl sectioned space 22l indicates a continuous Wall or pillar lei't. between thev coalrbodies D and E removed by lthe. slabbing operation. The possibility otleavingthesewalls as at 22 to 'torni Ya zigfzag supporting.medium,for the niinefroof is one of the most desirable ifea tures oftheminingsystem.: Thus, it may be seen that suitable root ,supports can be lett Whereverv necessary with aminimum amount or' timbering. and :little interference with the mining operations.v

As shoivn at 2l; thecslabbingf process as carried onzin the space/D mayV `beicontinued on along an. oblique face as Well as simply in liinesiparallel with theventries. Vorking alongV the oblique face las 4Well as-along the parallel face; serves to increase the lengthv of `face wli-ichecan be cutsin one cut or" vthe mining machine. Additional slabs ot coal maybe taken anywhere that 'roof and bottom conditions permit;

lWith a root of normalstrength, there is much Aless"danger of `its 'falling- Wherev the slabbing is carried out as above described and much .less timberingis `needed than when *the slabs cut` are all:` of the.l same length. y Y t ltl should.A be noted f that i this system of mining is not dependent on Aundercutting, butlwhere cuttingor Vundercuttingis mentioned7 it should he taken toy refer as Well te middlel cutting or top cutting or any other-Way of cuttinga.- slot or kerf in the coa-l,

Having thus describedl Whatil claim is :1

1. The method otminingra body` of coal lying between parallel entries Which consists in' breakingdown and `removing a relatively long slab along one entry, breaking down and removing successive paralell slabs yeach of less Alength than the preceding my invention,

V.as

slab so as to leave the face of the body of coal at an oblique angle to the direction of the entry.

2. The method of mining a body of coal lying between parallel entries which consists in breaking down and removing a relatively long slab along one entry, breaking down and removing successive parallel slabs each of less length than the preceding slab so as to leave the face of the body of' coal at an oblique angle to the direction of the entry, then breaking down and removing a slab along the other entry to a point beyond the line of the end of the slab first broken down along the first entry, breaking down and removing successive slabs each of less length than the preceding slab so that the face of the body of coal left at the conclusion of the second slabbing operation will be oblique to the line of the direction of the entries and will be at an angle opposite to the angle of the face left by the first slabbing operation.

3. The method of mining a body of' coal lying between parallel entries which consists in breaking down and removing a relatively long slab along one entry, breaking down and removing successive parallel slabs each of less length than the preceding slab so as to leave the face of the body i of coal at an oblique angle to the direction of the entry7 then breaking down and removing a slab along the other entry to a point beyond the line of the slab first broken down along the first entry, breaking down and removing successive slabs each of less length than the preceding slab so that the face of the body of coal left at the conclusion of the second slabbing operation will be oblique to the line of the direction of the entries and will be at an angle opposite to the angle of the 'face left by the first slabbing operation, and leaving a standing wall of coal oblique to the entries between the masses of coal.

4. The method of Ymining a body of coal lying between parallel entries which consists of breaking down and removing a relatively long slab along one entry, breaking down and removing successive parallel slabs each of less length than the preceding slab so as to leave the face of the body of coal at an oblique angle to the direction of the entry, portions of the coal in the line of a slab being left standing to serve as a support for the roof.

In testimony whereof I hereunto aiiix my signature.

JOSEPH POWER DAWSON. 

